A delegation from the Organisation of American States (OAS) has visited the site of a Colombian rebel camp inside Ecuador raided by the Colombian army.
The attack provoked the region's worst tensions in years
The OAS is investigating the events surrounding the attack which last week sparked a diplomatic crisis between Colombia and its neighbours.
Ecuador proposed an outside force to monitor the border but the head of the OAS says this would be difficult.
The OAS team is now in Colombia to continue its inquiries.
The crisis began after Colombian air and ground forces attacked a camp inside Ecuador, killing the Farc rebels' second-in-command Raul Reyes and more than 20 others.
Ecuador and Venezuela broke off diplomatic ties with Colombia in the worst diplomatic row in the region for years and sent extra troops to their respective borders.
Tensions were eased at a summit in the Dominican Republic on Friday and Venezuela has restored relations with Colombia.
The OAS, which also met last week to discuss the crisis, is conducting an inquiry and will present a report to an OAS meeting in Washington on 17 March.
The OAS team wanted to see for themselves the site of the attack
Delegates from several countries, including Argentina, Peru and Brazil, on Monday travelled to Angostura, some 250km (155 miles) north-east of Quito, where the raid took place.
"I think it was very important to come and visit the place and see exactly where the bombs fell and see as well where they didn't fall, to speak a bit with officials and military men that are present here and in such a way we have formed a picture of both things, from the point of view of Ecuador," said OAS Secretary General Jose Manuel Insulza.
Mr Insulza said the key issues were to investigate how the events happened and what needed to be done to avoid a repetition.
Ecuador has proposed that an OAS force or UN troops be deployed to monitor its border with Colombia.
Colombian President Alvaro Uribe has indicated he would not rule out such a proposal.
But Mr Insulza said that he did not believe such an idea was viable.
Mr Insulza and his delegation were set to hold talks with Colombian officials later on Tuesday.
The Colombian government Colombia has said it regrets conducting the cross-border raid but that it was necessary "in the fight against terrorism".
The Farc, which has been fighting the Colombian state for more than four decades, is viewed by the US and the EU as a terrorist group.